A freezeless wall hydrant is used to deliver water to the outside of a building. It consists of a fluid closure valve within a pipe located inside the outer wall of a building. The pipe extends through the wall, terminating with hose threads outside the outer wall. Attached to the fluid closure valve is an elongated operating rod that terminates with a handle outside the pipe. Operation of the handle outside the wall opens and closes the fluid closure valve inside the wall. The freezeless wall hydrant is installed at an angle so when the hydrant is off, the water in the pipe will drain outside the outer wall, preventing the water from freezing and damaging the pipe.
A problem occurs when a hose is left on the hydrant whose outlet is higher than the hydrant, or a valve is added to the end of the hose, preventing water from draining from the hydrant. Water trapped in the hydrant will freeze when temperatures drop below 32 degrees Fahrenheit. As the water freezes, it expands. The hydraulic action of the freezing water expanding increases pressure on the liquid portion of the water remaining in the hydrant pipe between the expanding ice and the closed fluid closure valve inside the pipe, causing the pipe to rupture. Once the weather warms in the spring and the hydrant is turned on, costly flooding of the building typically will occur. U.S. Pat. No. 6,142,172, referenced herein, concerns relieving this pressure by employing a simple pressure relief valve, made up of a ball and spring within the fluid closure valve that would relieve build-up pressure from the hydrant pipe back into the supply line. One problem with this method is that possible contaminated water, leached from the hose, can be forced back into the supply line to be distributed to drinking water sources throughout the building. Back flow and cross contamination are major concerns for all code officials regarding water quality. In addition, to ensure contaminated water is not forced back into the supply every time there is a differential pressure across the fluid closure valve, that pressure relief valve must be set to a very high relief pressure adding undue stress to the hydrant piping system. As the pressure relief valve ages and corrodes it is likely that it will no longer relieve the pressure in the pipes which could exceed the limits of the pipe and to burst the pipe.
Conventional fluid closure means incorporates a rubber washer compressed on a seat for closure. The rubber washer is attached to an inner member that reciprocates in the flow passage to open and close the valve. Subsequent conventional designs have employed the same rubber washer closure means attached to a telescoping “bullet” that would telescope out to the seat when the valve was in the open position to prevent back flow and backpressure. When the valve was in the closed position no movement of the bullet was possible as it was trapped between the operating rod and the seat.